A portal site for systems biology.

The CellML language is an open standard based on the XML markup language. CellML is being developed by the Auckland Bioengineering Institute at the University of Auckland and affiliated research groups.
http://www.cellml.org

SBML defines machine-readable representation of biological network models that are specifically aimed at simulation and sysem analysis.
http://sbml.org/

SBGN defines human-readable representation of biological network models in the most expressive and consistent manner.
http://sbgn.org/

BioPAX (Biological Pathways Exchange) is a collaborative effort to create a data exchange format for biological pathway data.
http://www.biopax.org/